1. Field of the Invention
The present invention is directed primarily to truck bodies designed specifically for refuse hauling trucks and, more particularly, to an improved tailgate mechanism for rear discharge hauling trucks, such as rear-loading refuse compacting trucks, which automates latching and unlatching of the tailgate to allow raising the tailgate and ejection or discharge of the contents by automated remote operation.
2. Description of the Related Art
Trucks for hauling various types of loads such as refuse pick-up trucks, rear discharge dump trucks, or the like, commonly include a truck chassis fitted with a distinctly configured separate body that is designed, built and installed on the chassis by a manufacturer other than the manufacturer of the chassis itself. The truck body is, then, specifically designed for the tasks to be accomplished. In the case of refuse trucks, it includes systems for receiving, compacting, hauling and discharging refuse materials and includes all the associated operating mechanisms. One very successful design of refuse hauling truck bodies is known as a "rear loader" and includes a refuse hauling reservoir accessible for loading and discharge from the rear of the vehicle. This system includes an hydraulic compacting mechanism which repeatedly compacts the refuse after each loading. In this manner, refuse eventually fills the available or usable reservoir volume extending from the front end back toward the rear of the body until no more material can be compacted.
The refuse holding reservoir is typically loaded through a rather large tailgate section which forms the closure for the rear of the refuse holding reservoir and includes a receiving hopper into which general refuse, cans or the like, can be dumped. The system further includes a packer blade mechanism which moves the refuse from the hopper into the body of the vehicle. Both the hopper and the packer blade mechanism are contained in and supported by a tailgate section.
The tailgate is hingedly connected to the truck body at the top rear of the truck body and may be raised to completely open the rear of the reservoir. The bottom of the tailgate, when lowered or in the closed position, is secured by latches to the rear structural supports on either side of the refuse truck body. The system is operated with the tailgate down and latched to the truck body except during the ejection of the accumulated contents at which time the tailgate is unlatched and swung upward and out of the way opening the entire rear of the refuse holding reservoir so that the collected material may be discharged from the body of the truck beneath the raised tailgate.
With a manual system, the truck operator must leave the cab to unlatch both sides of the tailgate from the truck body by hand at the landfill prior to backing up to the trash pit or landfill. This may also result in some spillage. He then backs up to the discharge pit and operates a pair of hydraulic cylinders connected between the tailgate and the truck body to raise the tailgate upward and operates the ejector mechanism to expel the contents of the reservoir. The hydraulic pressure is then relieved and the tailgate allowed to return to the normal position by gravity. The operator must again leave the cab to relatch the tailgate by hand.
The operation of the tailgate mechanism, thus, requires the driver of the vehicle to leave the cab twice, i.e., to unlatch both sides of the tailgate by hand prior to actuating the cylinders for lifting of the tailgate and, after ejection, to relatch the tailgate by hand. With regard to performing this sequence of operation, it has been found that most injuries to refuse workers with respect to the picking up, hauling and discharge of refuse occur in performing the functions related to emptying the storage container of the rear loading compactor at the transfer pit or landfill. This is occasioned, in no small part, by the necessity of the driver of the truck to leave his cab and operate the latching and unlatching mechanisms of the truck.
It will be appreciated that the ejection mechanism moves the entire forward wall of the truck body against which the refuse is compacted aft on an horizontal plane, in the manner of a plow blade, to expel the entire contents of the refuse volume during ejection. The ejector is operated by an hydraulic cylinder which mounts behind the cab and moves the ejector system fore and aft. The tailgate therefore must be capable of being raised to and held at a sufficient height so that the ejector can operate underneath without contacting the tailgate.
It would be advantageous if the ejection or discharge function, taking place at the landfill for trucks of the rear loading class, could be automated so that the operator of the vehicle would not be required to manually unlatch and relatch the tailgate. One such device is illustrated and described in U.S. Pat. No. 3,440,763 to O'Brien in which an hydraulic cylinder is utilized to operate a closure member. That system utilizes a bell crank and operating rod to engage and disengage a latch pin rigidly attached to the operating rod. While some success has been experienced with such a device, it is mechanically complex and requires repeated perfect alignment for the pin to be replaced when closing the tailgate. This realignment often fails necessitating manual assistance in the relatching of the tailgate.
A need remains for a rather simple, self-aligning automatic latching system which is more dependable. This is especially true for haulers serving an area that uses transfer stations including transfer pits. It would reduce spillage and dumping or ejection time. There is also a need for such a system which can readily replace a manually operated system in the manner of a retrofit.